Nl - Netlink libraries for Ruby

require 'nl/linux'
require 'ipaddr'

# List IP addresses by interface
Nl::Raw::Client.open(protonum: Nl::Raw::NETLINK_ROUTE) do |client|
  rtaddr = client.family(Nl::Linux::RtAddr)
  rtlink = client.family(Nl::Linux::RtLink)

  links = rtlink.dump_getlink.to_h { |link| [link.ifi_index, link] }

  rtaddr.dump_getaddr.group_by(&:ifa_index).each do |ifindex, addrs|
    ips = addrs.map { |addr| "#{IPAddr.new_ntoh(addr.address)}/#{addr.ifa_prefixlen}" }
    link = links.fetch(ifindex)

    puts "#{link.ifname}: #{ips.join(', ')}"
  end
end

# List interface speeds
Nl::Linux::Ethtool.open do |ethtool|
  ethtool.dump_linkmodes_get.each do |dev|
    puts "#{dev.header.dev_name}: #{dev.speed} Mbps"
  end
end